[Qemu-devel] [patch 1/4] block: add bdrv_find_backing_image

[Marcelo Tosatti <mtosatti@redhat.com>]

[-- Attachment #1: bdrv-stream-shared-base-helpers --]
[-- Type: text/plain, Size: 1513 bytes --]

Add bdrv_find_backing_image: given a BlockDriverState pointer, and an id,
traverse the backing image chain to locate the id.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: stefanha/block.c
===================================================================
--- stefanha.orig/block.c
+++ stefanha/block.c
@@ -2580,6 +2580,24 @@ int bdrv_snapshot_load_tmp(BlockDriverSt
     return -ENOTSUP;
 }
 
+BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, const char *id)
+{
+    if (!bs->drv) {
+        return NULL;
+    }
+
+    if (bs->backing_hd) {
+        if (strncmp(bs->backing_file, id, sizeof(bs->backing_file)) == 0) {
+            return bs->backing_hd;
+        } else {
+            return bdrv_find_backing_image(bs->backing_hd, id);
+        }
+    }
+
+    return NULL;
+}
+
+
 #define NB_SUFFIXES 4
 
 char *get_human_readable_size(char *buf, int buf_size, int64_t size)
Index: stefanha/block.h
===================================================================
--- stefanha.orig/block.h
+++ stefanha/block.h
@@ -146,6 +146,7 @@ int coroutine_fn bdrv_co_writev(BlockDri
     int nb_sectors, QEMUIOVector *qiov);
 int coroutine_fn bdrv_co_is_allocated(BlockDriverState *bs, int64_t sector_num,
     int nb_sectors, int *pnum);
+BlockDriverState *bdrv_find_backing_image(BlockDriverState *bs, const char *id);
 int bdrv_truncate(BlockDriverState *bs, int64_t offset);
 int64_t bdrv_getlength(BlockDriverState *bs);
 int64_t bdrv_get_allocated_file_size(BlockDriverState *bs);